With the increased use of fiber optics in telephone and other communication circuits the use of laser devices in amplifying repeating apparatus in the optical communication channels is widespread. Laser devices permit transmission of a plurality of signal channels covering a wide bandwidth range and hence are suitable for both traditional voice channels and varied high rate data and high frequency signal channels all transmitted over a single optical fiber transmission line.
In order to handle a plurality of channels over a wide bandwidth without distortion, the laser device must be operated within its linear temperature region defined by a very narrow operating temperature range. Should the operating temperature of the laser device fall outside of this narrow range the laser device no longer linearly transmits the communication channels over the entire range of the normal bandwidth of the device. Hence in an actual operating environment having a wide range of ambient temperatures, it is necessary to provide temperature control apparatus to maintain the operating temperature of the laser amplifying device within its specified operating temperature range.